Hydrocarbon combustion power generation system with CO2 sequestration

ABSTRACT

A low or no pollution engine is provided for delivering power for vehicles or other power applications. The engine has an air inlet which collects air from a surrounding environment. At least a portion of the nitrogen in the air is removed using a technique such as liquefaction, pressure swing adsorption or membrane based air separation. The remaining gas is primarily oxygen, which is then compressed and routed to a gas generator. The gas generator has an igniter and inputs for the high pressure oxygen and a high pressure hydrogen-containing fuel, such as hydrogen, methane or a light alcohol. The fuel and oxygen are combusted within the gas generator, forming water and carbon dioxide with carbon containing fuels. Water is also delivered into the gas generator to control the temperature of the combustion products. The combustion products are then expanded through a power generating device, such as a turbine or piston expander to deliver output power for operation of a vehicle or other power uses. The combustion products, steam and, with carbon containing fuels, carbon dioxide, are then passed through a condenser where the steam is condensed and the carbon dioxide is collected or discharged. A portion of the water is collected for further processing and use and the remainder is routed back to the gas generator. The carbon dioxide is compressed and cooled so that it is in a liquid phase or super critical state. The dense phase carbon dioxide is then further pressurized to a pressure matching a pressure, less hydrostatic head, existing deep within a porous geological formation, a deep aquifer, a deep ocean location or other terrestrial formation from which return of the CO2 into the atmosphere is inhibited.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International ApplicationNo. PCT/US97/17006 filed on Jun. 7, 1995, which designates the UnitedStates for a continuation-in-part application U.S. Pat. No. 5,680,764.

This application incorporates by reference the contents of U.S. Pat. No.5,709,077.

FIELD OF THE INVENTION

This invention contains environmentally clean engine designs that emitzero or very low pollutant levels during operation. The CLEAN AIR ENGINE(CLAIRE) invention is directly applicable to both transportation typevehicles including automobiles, trucks, trains, airplanes, ships and tostationary power generation applications. The designs feature hybrid,dual cycle and single cycle engines. More specifically, this inventionrelates to low or no pollution generating hydrocarbon combustion basedpower generation systems which isolates and conditions carbon dioxide(CO2) generated in the system for injection and sequestering intoterrestrial formations such as underground geological formations andoceans.

BACKGROUND OF THE INVENTION

The current art in generating power for transportation purposesbasically utilize the internal combustion gas or diesel engine. Thecurrent art for electric power generation utilize gas turbines and/orsteam turbines. These devices burn hydrocarbon fuels with air whichcontains (by weight) 23.1% oxygen, 75.6% nitrogen and the remaining 1.3%in other gases. The emissions resulting from the combustion of fuels forinternal combustion engines (gasoline or diesel), with air contain thefollowing pollutants that are considered damaging to our airenvironment. These smog causing pollutants, are: total organic gases(TOG); reactive organic gases (ROG); carbon monoxide (CO); oxides ofnitrogen (NOx); oxides of sulfur (SOx); and particulate matter (PM).Approximately one half of the total pollutants emitted by all sources ofair pollution in California are generated by road vehicles (EmissionInventory 1991, State of California Air Resources Board, preparedJanuary 1994). The major source of this vehicle pollution comes frompassenger cars and light to medium duty trucks.

No near term solutions appear in sight to drastically reduce the vastamount of air pollutants emitted by the many millions of automobiles andtrucks operating today. Based on the State of California Air ResourcesBoard study, the average discharge per person in California of the airpollutants from mobile vehicles, monitored by this agency during 1991and reported in 1994, was approximately 1.50 lb/day per person. With anationwide population of over 250,000,000 people, this data extrapolatesto over 180,000 tons of air borne emissions per day being discharged inthe USA by mobile vehicles. Also, the number of cars and miles that arebeing driven continue to increase, further hampering efforts to reducesmog causing pollutants.

Allowable emission thresholds are rapidly tightening by Federal andState mandates. These allowable emission reductions are placing severedemands on the transportation industry and the electric power generatingindustry to develop new and lower emission power systems.

Although considerable effort is being directed at improving the range ofelectric zero emission vehicles (ZEV) by developing higher energycapacity, lower cost storage batteries, the emission problem is beentransferred from the vehicle to the electric power generating plant,which is also being Federally mandated (Clean Air Act Amendments of1990) to reduce the same air toxic emissions as those specified forautomobiles and trucks.

The current world wide art of generating power for consumers ofelectricity depends primarily on fossil fuel burning engines. Theseengines burn hydrocarbon fuels with air. As described above, combustionof fossil fuels with air usually produce combustion products thatcontain a number of pollutants. Current Unites States regulatoryrequirements prescribe the amounts of the atmospheric pollutantspermitted in particular locations. Allowable pollutant thresholds aredecreasing over time and thereby putting more and more pressure onindustry to find better solutions to reduce these emissions ofpollutants in the electric power generating industry and other powergenerating industries.

Other energy sources being developed to solve the emissions problem, byexploiting non combustible energy sources include fuel cells and solarcells. Developers are solving many of the technological and economicproblems of these alternate sources. However, widespread use of theseenergy sources for vehicles and for electric power generating facilitiesdo not appear to yet be practical.

In addition to the emission of pollutants, combustion based powergeneration systems also generate significant amounts of carbon dioxide(CO2). While CO2 emissions are currently not regulated in the UnitedStates, concern has been voiced by experts over the release of CO2 andother greenhouse gases into the environment. One method for eliminatingthe formation of CO2 in combustion based power generation systems is toutilize hydrogen as the fuel rather than a hydrocarbon fuel. Use ofhydrogen as a fuel has many drawbacks including the highly flammable andpotentially explosive nature of hydrogen when in a gaseous state, thesignificant energy required to maintain hydrogen in a liquid state, thelow density of hydrogen requiring large volumetric storage capacity andthe fact that all present commercial production of hydrogen comes fromfossil fuels which also yield CO2 as a by-product.

Some attention has recently been given to the concept of separating theCO2 from other combustion products and then disposing of the CO2 byinjecting it into deep porous geological formations or deep into theearth's oceans where environmental impacts of the release of the CO2would be minimized. Interest in such terrestrial formation disposaltechniques is exemplified by the recent issuance by the United StatesDepartment of Energy of a Small Business Innovation Research (SBIR)program solicitation (reference number DOE/ER-0706, closing date Mar. 2,1998) specifically seeking strategies for mitigation of greenhouse gasesand pollutants including CO2. This solicitation sought approaches to CO2disposal involving usage of potential storage sites such as oil and gasreservoirs, unmineable coal seams, the deep ocean, or deep confinedaquifers. CO2 separation and injection systems are known in the priorart but the CO2 is only partially separated and the processes are soenergy intensive that such systems are not generally commerciallyviable. Accordingly, a need exists for such a more efficient CO2separation and injection system which can sequester and dispose of theCO2 in an economically viable manner.

SUMMARY OF THE INVENTION

This invention provides a means for developing a zero or very lowpollution vehicle (ZPV) and other transportation power systems (i.e.rail and ship), as well as a zero or low pollution electric powergenerating facility. The zero or very low pollution is achieved byremoving the harmful pollutants from the incoming fuel and oxidizerreactants prior to mixing and burning them in a gas generator orcombustion chamber. Sulfur, sulfides and nitrogen are major pollutantsthat must be removed from the candidate fuels: hydrogen, methane,propane, purified natural gas, and light alcohols such as ethanol andmethanol. Since air contains 76% nitrogen by weight, it becomes a majorsource of pollution that also requires removal prior to combining itwith the clean fuel.

Cleansing of the fuel is straightforward and requires no furtherelaboration. The separation of the oxygen from the nitrogen in the air,however, is accomplished in a variety of ways. For instance, nitrogencan be removed from air by the liquefaction of air and gradualseparation of the two major constituents, oxygen and nitrogen, by meansof a rectifier (to be described later in more detail). The separation ofthe gases relies on the two distinct boiling points for oxygen (162° R)and for nitrogen (139° R) at atmospheric pressure. Air liquefies at anintermediate temperature of (142° R).

Other nitrogen removal techniques include vapor pressure swingadsorption, and membrane based air separation. With vapor pressure swingadsorption, materials are used which are capable of adsorption anddesorption of oxygen. With membrane based air separation, an air feedstream under pressure is passed over a membrane. The membrane allows onecomponent of the air to pass more rapidly there through than othercomponents, enriching the amount of different components on oppositesides of the membrane. Such membranes can be of a variety of differentmaterials and use several different physical processes to achieve thedesired separation of nitrogen out of the air.

One embodiment of this invention consists of a hybrid power system thatcombines a Rankine cycle thermal cycle with an auxiliary electric motorfor start-up and chill-down requirements. The thermal power cycle of theengine begins by compressing ambient air to high pressures, cooling theair during compression and during the expansion to liquid airtemperatures in a rectifier where separation of the oxygen and nitrogentakes place. The cold gaseous nitrogen generated is used to cool theincoming air and then is discharged to the atmosphere at near ambienttemperature. Simultaneously, the cold gaseous or liquid oxygen generatedby the rectifier is pressurized to gas generator pressure levels anddelivered to the gas generator at near ambient temperature. Fuel,gaseous or liquid, from a supply tank is pressurized to the pressurelevel of the oxygen and also delivered to the gas generator where thetwo reactants are combined at substantially the stoichiometric mixtureratio to achieve complete combustion and maximum temperature hot gases(6500° R). These hot gases are then diluted with water downstream in amixing section of the gas generator until the resulting temperature islowered to acceptable turbine inlet temperatures (2000° R).

The drive gas generated from this mixing process consists of high puritysteam, when using oxygen and hydrogen as the fuel, or a combination ofhigh purity steam and carbon dioxide (CO2), when using oxygen and lighthydrocarbon fuels (methane, propane, methanol, etc.). Following theexpansion of the hot gas in the turbine, which powers the vehicle or theelectric power generating plant, the steam or steam plus CO2 mixture arecooled in a condenser to near or below atmospheric pressure where thesteam condenses into water, thus completing a Rankine cycle.Approximately 75% of the condensed water is recirculated to the gasgenerator while the remainder is used for cooling and discharged to theatmosphere as warm water vapor. When using light hydrocarbons as thefuel, the gaseous carbon dioxide remaining in the condenser iscompressed to slightly above atmospheric pressure and either convertedto a solid or liquid state for periodic removal, or the gas can bedischarged into the atmosphere when such discharge is considerednon-harmful to the local air environment.

Since this thermal cycle requires time to cool the liquefactionequipment to steady state low temperatures, an electric motor, driven byan auxiliary battery, can be used to power the vehicle and initiate theRankine cycle until chill-down of the liquefaction equipment isachieved. When chill-down is complete the thermal Rankine engine,connected to an alternator, is used to power the vehicle or stationarypower plant and recharge the auxiliary battery.

The combination of these two power systems, also referred to as a hybridvehicle, emit zero or very low pollution in either mode of operation. Inaddition, the electric motor battery is charged by the zero or very lowpollution thermal Rankine cycle engine itself and thus does not requirea separate electric power generating plant for recharge. This reducesthe power demand from central power stations and also reduces apotential source of toxic air emissions.

In place of the electric drive motor and battery, the Rankine cycleengine, with the addition of a few control valves, can also be operatedas a minimally polluting open Brayton cycle, burning fuel and incomingair to power the vehicle during the period necessary to allow theRankine cycle engine liquefaction equipment time to chill-down. Thisfeature is another embodiment of this invention.

The zero or very low pollution Rankine cycle engine can also be used ina single cycle thermal mode for vehicles with long duration continuousduty such as heavy trucks, trains, ships and for stationary powergeneration plants where the chill-down time is not critical to theoverall operational cycle.

The adaptation of the Otto and Diesel thermal cycles to a low-pollutinghybrid engine are also included as embodiments of this invention. Byusing these thermal cycles, the need for a condenser and recirculatingwater system are eliminated. Low temperature steam or steam/carbondioxide gases are recirculated as the working fluid and thereforereplace the function of the recirculating water quench of the Rankinecycle embodiments previously discussed.

The combustion products resulting from operation of the above-describedengine are substantially entirely H2O and CO2 (when a hydrocarbon fuelis used). These combustion products are in contrast to combustionproducts resulting from typical hydrocarbon combustion based powergeneration systems which do not have an air constituent separationdevice, as identified above. Combustion products in such prior artsystems would also include a large amount of nitrogen and unused oxygenas well as NOx and various carbon containing species. Because thecombustion products resulting from the above-described engine are merelyH2O and CO2, the isolation and conditioning of CO2 is straight forwardand draws little power away from the system as a whole.

Specifically, the combustion products are passed through a condenserwhere the H2O condenses into a liquid phase. Gases exiting the condenserare substantially only carbon dioxide and can be directed out of thecondenser for use in a terrestrial formation injection system or otherdisposal, such as for use in industrial processes requiring CO2. To mosteffectively inject the CO2 into a deep terrestrial formation, the CO2must be pressurized. Such formations include oceans; deep aquifers; andporous geological formations such as partially or fully depleted oil orgas formations, salt caverns, sulfur caverns and sulfur domes. Toaccomplish such pressurization the gaseous CO2 can be compressed in oneor more stages with after cooling and condensation of additional water.The modestly pressurized CO2 can then be further dried by conventionalmethods such as through the use of molecular sieves and passed to a CO2condenser where the CO2 is cooled and liquefied. The CO2 can then beefficiently pumped with minimum power to a pressure necessary to deliverthe CO2 to a depth within the geological formation or the ocean depth atwhich CO2 injection is desired. Alternatively, the CO2 can be compressedthrough a series of stages and discharged as a super critical fluid at apressure matching that necessary for injection into the geologicalformation or deep ocean.

OBJECTS OF THE INVENTION

Accordingly, a primary object of the present invention is to provide alow or zero pollution combustion based power generation system whichadditionally isolates and conditions CO2 from combustion productsdischarged by the system for effective handling of the CO2 in a mannerother than release of the CO2 into the atmosphere.

Another object of this invention is to provide a high efficiencycombustion based power generation system.

Another object of the present invention is to provide a power generationsystem which can also produce water as a byproduct. In areas where wateris scarce the water byproducts produced by this invention areparticularly beneficial.

Another object of the present invention is to provide a combustion basedpower generation system which includes an air treatment plant forseparating nitrogen from the air prior to use of the air to combust ahydrocarbon fuel, such that nitrogen oxides and other pollutants arereduced or eliminated as byproducts of combustion in the powergeneration system.

Another object of the present invention is to provide a hydrocarboncombustion based power generation system which injects CO2 produced bythe power generation system into a terrestrial formation such as a deepporous geological structure or an undersea location.

Another object of the present invention is to provide a combustion basedpower generation system which releases no combustion products into theatmosphere.

Another object of the present invention is to provide a reliable andeconomical source of power which does not harm the surroundingenvironment.

Other further objects of this invention will become apparent upon acareful reading of the included description of the invention and reviewof the drawings included herein, as well as the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustrating an embodiment of this invention andits elements, along with their connectivity. This embodiment constitutesa very low pollution or pollution-free hybrid power system for vehicularand other applications. The fuel reactant is a light hydrocarbon typesuch as methane propane, purified natural gas, and alcohols (i.e.methanol, ethanol).

FIG. 2 is a schematic illustrating an embodiment of this invention whichis also a very low pollution or pollution-free hybrid power system forvehicular and other applications where the fuel is gaseous hydrogen.

FIG. 3 is a schematic illustrating an embodiment of this invention whichis a very low pollution or pollution-free power system for vehicular andother applications during cruise and continuous duty. During start-upand a short period thereafter, the engine runs in an open Brayton cyclemode and thus emits some pollutants.

FIG. 4 is a plot of Temperature v. Entropy for the working fluidillustrating the first of two cycles used in the dual mode engine ofFIG. 3. This cycle is an open Brayton with inter-cooling betweencompressor stages (Mode I).

FIG. 5 is a plot of Temperature v. Entropy for the working fluidillustrating the second cycle used in the dual mode engine of FIG. 3.This cycle is a Rankine with regeneration, (Mode II).

FIG. 6 is a schematic illustrating an embodiment of this invention andits interconnecting elements. This embodiment constitutes a very lowpollution or pollution-free hybrid power system for vehicular and otherapplications similar to that of FIG. 1 but with the addition of tworeheaters to the power cycle for improved performance. The fuel reactantfor this cycle is a light hydrocarbon.

FIG. 7 is a schematic illustrating an embodiment of this invention andits interconnecting elements. This embodiment constitutes a very lowpollution or pollution-free hybrid power system similar to that of FIG.2 but with the addition of two reheaters to the power cycles forimproved performance. The fuel reactant for this cycle is hydrogen.

FIG. 8 is a plot of Temperature v. Entropy for the working fluid for thepower cycle used for the thermal engines shown in FIG. 6 and FIG. 7.This cycle features the Rankine cycle with regeneration and reheat forimproved performance.

FIG. 9 is a schematic illustrating an embodiment of this invention thatfeatures a very low pollution or non-polluting hybrid engine withelectric motor drive and a Rankine power cycle utilizing dynamic typeturbomachinery. The Rankine power cycle utilizes regeneration andreheaters for increased cycle efficiency and power density.

FIG. 10 is a schematic illustrating an embodiment of this invention thatfeatures a low polluting hybrid engine with an electric motor drive andan Otto power cycle reciprocating engine.

FIG. 11 is a schematic illustrating an embodiment of this invention thatfeatures a low polluting hybrid engine with an electric motor drive anda Diesel power cycle reciprocating engine.

FIG. 12 is a schematic illustrating a basic low-polluting engine where arectifier and air liquefaction devices of previous embodiments arereplaced with an air separation plant which separates nitrogen from airby any of a variety of techniques including liquefaction, vapor pressureswing adsorption, membrane based air separation, etc.

FIG. 13 is a schematic similar to that which is shown in FIG. 12 butincluding regeneration in the cycle disclosed therein.

FIG. 14 is a schematic similar to that which is disclosed in FIGS. 12and 13 except that a duel cycle arrangement is provided which features abottoming cycle for enhanced efficiency.

FIG. 15 is a schematic of a typical pressure swing adsorption plant foruse as the air separation plant in one of the engines disclosed in FIGS.12-14.

FIG. 16 is a schematic of a membrane flow two stage enrichment of oxygenand nitrogen system for use as part of the air separation plant of thecycles disclosed in FIGS. 12-14.

FIG. 17 is a system diagram of the hydrocarbon combustion powergeneration system of this invention with CO2 compression andliquefaction for injection into a terrestrial formation.

FIG. 18 is a flow chart indicating the basic components of the powergeneration system of this invention and revealing where materials enterinto the system and where materials exit from the system anddemonstrating the absence of atmospheric disruption when the powergeneration system of this invention is in operation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the first embodiment of the present invention, a zero orvery low pollution Rankine cycle thermal engine operating in parallelwith a zero emissions electric motor (also referred to as a hybridengine) is illustrated in FIG. 1. The Rankine engine consists of adynamic turbocompressor 10, a reciprocating engine 20, a powertransmission 30, a heat exchanger 40, a turboexpander 50, a rectifier60, a gas generator 70, a condenser 80, a recirculating water feed pump90, a water heater 100 and a condenser coolant radiator 110. Theelectric engine consists of an alternator 120, a battery 130 andelectric motor 140.

Hybrid engine operation begins by starting the electric motor 140 usingthe battery 130 as the energy source. The electric motor 140 drives thereciprocating engine 20 through the power transmission 30 and therebyinitiates the start of the thermal engine that requires a chill-downperiod for the liquefaction equipment consisting of heat exchanger 40,turboexpander 50 and rectifier 60.

Activation of the thermal engine initiates the compression of ambienttemperature air from a surrounding environment entering the dynamiccompressor 2 through an air inlet duct 1. The compressor 2 raises theair to the design discharge pressure. The air then exits through duct 3into intercooler 4 where the heat of compression is removed by externalcooling means 5 (i.e. air, water, Freon, etc.). Condensed water vaporfrom the air is tapped-off by drain 6. After the air exits intercooler 4through duct 7, at a temperature equal to the compressor inlet, itenters the reciprocating compressor 8 and is raised to the designdischarge pressure. The air exits through duct 9 into intercooler 11 andis again cooled to the inlet temperature of the compressor. Thiscompression/cooling cycle is repeated as the air exits intercooler 11through duct 12 and enters reciprocating compressor 13, then exitsthrough duct 14, enters intercooler 15 and exits through duct 16, tocomplete the air pressurization.

The high pressure, ambient temperature air then enters the scrubber 17where any gases or fluids that could freeze during the subsequentliquefaction are removed. These gases and liquids include carbon dioxide(duct 18 a and storage tank 18 b), oil (line 19 a and storage tank 19 b)and water vapor (tap off drain 21). The oil can be from a variety ofsources, such as leakage from the air compression machinery. The dry airthen exits through duct 22 and enters heat exchanger 40 where the air iscooled by returning low temperature gaseous nitrogen.

The dry air is now ready to pass through an air treatment device for theseparation of nitrogen out of the air and to provide nitrogen freeoxygen for combustion as discussed below. The dry air will contain, byweight, 23.1% oxygen, 75.6% nitrogen, 1.285% argon and small traces ofhydrogen, helium, neon, krypton and xenon (total of 0.0013%). Argon hasa liquefaction temperature of 157.5° R, which lies between the nitrogenand oxygen boiling points of 139.9° R and 162.4° R respectively.Therefore argon, which is not removed, will liquefy during theliquefaction process. The remaining traces of gases hydrogen, helium andneon are incondensable at temperatures above 49° R while krypton andxenon will liquefy; however, the trace amounts of these latter gases isconsidered insignificant to the following air liquefaction process.

The dry air then exits through duct 23 and enters the turboexpander 24where the air temperature is further reduced to near liquid airtemperature prior to exiting duct 25 and enters the rectifier 60 (a twocolumn type design is shown). Within the rectifier, if not before, theair is cooled to below the oxygen liquefaction temperature. Preferably,a two column type rectifier 60 is utilized such as that described indetail in the work: The Physical Principles of Gas Liquefaction and LowTemperature Rectification, Davies, first (published by Longmans, Greenand Co. 1949).

The air exits from the lower rectifier heat exchanger 26 through duct 27at liquid air temperature and enters the rectifier's lower column plateswhere the oxygen/nitrogen separation is initiated. Liquid with about 40%oxygen exits through duct 28 and enters the upper rectifier column wherea higher percentage oxygen concentration is generated. Liquid nitrogenat 96% purity is recirculated from the lower rectifier column to theupper column by means of duct 29. Gaseous nitrogen at 99% purity (1%argon) exits through duct 31 and enters heat exchanger 40 where coolingof the incoming air is performed prior to discharging through duct 32 tothe atmosphere at near ambient temperature and pressure. Gaseous orliquid oxygen at 95% purity (5% argon) exits through duct 33 and entersthe turboexpander compressor 34 where the oxygen is pressurized to thedesign pressure. The high pressure oxygen then exits through duct 35 andenters the gas generator 70.

A light hydrocarbon fuel (methane, propane, purified natural gas andlight alcohols such as ethanol and methanol) exits the fuel supply tank37 through duct 38 and enters the reciprocating engine cylinder 39 wherethe fuel is raised to the design discharge pressure. The fuel then exitsthrough duct 41 and enters the gas generator 70 to be mixed with theincoming oxygen at the stoichiometric mixture ratio to achieve completecombustion and maximum hot gas temperature (approximately 6500° R). Thegas generator includes an ignition device, such as a spark plug, toinitiate combustion. While the gas generator 70 is the preferred form offuel combustion device for this embodiment, other fuel combustiondevices could also be used, such as those discussed in the alternativeembodiments below. The products of combustion of these reactants resultin a high purity steam and carbon dioxide gas and a small amount ofgaseous argon (4%).

Following the complete combustion of the high temperature gases,recirculating water is injected into the gas generator 70 through line42 and dilutes the high temperature gases to a lower temperature drivegas acceptable to the reciprocating engine (approximately 2000° R). Thiswater influx also increases a mass flow rate of combustion productsavailable for expansion and power generation. The drive gas then exitsthe gas generator 70 through discharge duct 43, enters reciprocatingcylinder 44, expands and provides power to the power transmission 30.Other combustion product expansion devices can replace the reciprocatingcylinder 44, such as the dynamic turbines discussed in the sixthembodiment below. The gas exits through duct 45, enters the secondcylinder 46, expands and also provides power to the power transmission;the gas exits through duct 47 and powers the dynamic turbine 48 whichdrives the centrifugal compressor 2, which was driven by the electricmotor 140 during start-up, and the alternator 120 to recharge thebattery 130.

The gas then exits through duct 49, enters the water heater 100 whereresidual heat in the gas is transferred to the recirculating water beingpumped by pump 90, the water heater gas exits through duct 51, entersthe condenser 80 at near or below atmospheric pressure, wherecondensation of the steam into water and separation of the carbondioxide takes place. The condensed water exits through line 52, entersthe pump 90 where the pressure of the water is raised to the gasgenerator 70 supply pressure level. A major portion of the pump 90discharge water exits through line 53, enters the water heater 100 whereheat is transferred from the turbine 48 exhaust gas and then exitsthrough line 42 for delivery to the gas generator 70. The remainingwater from the discharge of pump 90 exits through duct 54 and is sprayedthrough nozzles 55 into radiator 110 (evaporative cooling). Coolant forthe condenser gases is recirculated through duct 56 to the radiator 110where heat is rejected to atmospheric air being pumped by fan 57.

The gaseous carbon dioxide, remaining after the condensation of thesteam, exits the condenser 80 through duct 58 and enters thereciprocating cylinder 59, (when the condenser pressure is belowatmospheric) compressed to slightly above atmospheric pressure anddischarged through duct 61. The compressed carbon dioxide can be storedin storage tank 62 and converted to a solid or liquid state for periodicremoval; or the gas can be discharged into the atmosphere when suchexpulsion is permitted.

It should be noted that this hybrid engine generates its own waterrequirements upon demand and thus eliminates the freezing problem of asteam Rankine cycle in a cold (below freezing) environment. Also, theengine generates its oxidizer requirements on demand and thus eliminatesmany safety concerns regarding oxygen storage.

A second embodiment of this invention, illustrated in FIG. 2, features ahybrid engine when using hydrogen in place of a hydrocarbon fuel. Whenusing hydrogen as the fuel no carbon dioxide is generated and only highpurity steam exits from the gas generator 70. Consequently all systemsrelated to carbon dioxide are deleted, and no other changes arebasically required. However, to maintain the same six cylinder engine ofFIG. 1, the hydrogen fuel FIG. 2 exits the fuel supply tank 37 throughduct 63, enters reciprocating engine cylinder 59, exits through duct 64,enters reciprocating engine cylinder 39, exits through duct 41 and isdelivered to the gas generator 70. This permits two stages ofcompression for the low density hydrogen.

A third embodiment of this invention, illustrated in FIG. 3, features adual cycle engine where a Brayton cycle is used for start-up andchill-down of the air liquefaction equipment (Mode I) and a Rankinecycle is used for cruise, idle and continuous duty (Mode II). Toincorporate this feature, high pressure air is tapped-off from cylinder13 (air pressurization as previously described for embodiment one) bymeans of bypass air duct 71 and modulated by valve 72. Also,recirculating water to the gas generator is modulated by means of valve73 to control the combustion temperature of the fuel and oxygen and theexit temperature of the gaseous mixture being delivered to power thecycle through duct 43.

The thermodynamic cycles for these two operating Modes are illustratedin FIG. 4 and FIG. 5. The working fluid for power cycle operation inMode I consists of steam, carbon dioxide and gaseous air. When operatingin Mode II the working fluid (as discussed in embodiment one and two)consists of steam and carbon dioxide when using hydrocarbon fuel andsteam only when using hydrogen.

An open Brayton cycle, illustrated in FIG. 4, with two stages ofintercooling the compressed air, 74 a, and 74 b, is used to power theengine during Mode I and initiates the chill-down of the liquefactionequipment for subsequent Mode II operation of the Rankine cycle withregeneration 75, illustrated in FIG. 5. Note that this embodimenteliminates the need for an electric motor, battery and alternator.

A fourth embodiment of this invention, illustrated in FIG. 6, includesall the elements of the first embodiment and adds two reheaters 150 and160 to improve the performance of this engine. While two reheaters 150,160 are shown, any number of reheaters can be utilized depending on therequirements of each specific application.

The engine operates as described for the first embodiment but with thefollowing changes. Hot gases exiting reciprocating cylinder 44 exitthrough duct 81, enter the reheater 150 where additional lighthydrocarbon fuel and oxygen is injected through ducts 88 and 89respectively. The heat of combustion of these reactants within thereheater 150 raises the incoming gas temperature to the level of the gasgenerator 70 output. The reheated gas then exits reheater 150 throughduct 82, enters reciprocating cylinder 46, expands and exits throughduct 83 and enters reheater 160 where additional oxygen and fuel isinjected. The heat of combustion of these reactants within the reheater160 again raises the incoming gas temperature to the same level as atthe gas generator 70 output. The heated gas then exits through duct 84and enters the dynamic turbine 48, as described previously in the firstembodiment. Fuel for the reheater 160 is supplied through duct 86. Theoxygen is supplied through duct 87.

A fifth embodiment of this invention, illustrated in FIG. 7, includesall the elements of the second embodiment and adds two reheaters 150 and160 to improve the performance. This engine operates as described forembodiment four except this engine uses hydrogen fuel. The Rankine cycleof these embodiments using regeneration and reheats is illustrated inFIG. 8. Regeneration is illustrated by 91 and the two reheats areillustrated by 92 a and 92 b.

A sixth embodiment of this invention; illustrated in FIG. 9, is similarto the fourth embodiment featuring reheaters, illustrated in FIG. 6,except all the machinery consists of dynamic type compressors andturbines. This type of machinery is more suitable for higher powerlevels (>1000 Shaft Horsepower (SHP)) required for rail, ship or standbypower systems.

The Rankine engine consists of dynamic turbocompressors 200, 210, and220, a power transmission 230, a heat exchanger 240, a turboexpander250, a rectifier 260, a gas generator 270, a first reheater 280, asecond reheater 290, a water heater 300, a condenser 310, arecirculating pump 320 and a condenser coolant radiator 330. Theelectric engine consists of an alternator 400, a battery 410 andelectric motor 420.

Engine operation begins by starting the electric motor 420 using thebattery 410 as the energy source. The electric motor 420 drives thedynamic compressor 201 through power transmission 230, andsimultaneously, valve 202 is opened and valve 203 is closed. Thisinitiates the start of the engine in a Brayton cycle mode. As enginespeed increases valve 202 is gradually closed and valve 203 is graduallyopened to slowly transition into the Rankine cycle mode and permit theliquefaction equipment to chill down. During this transitional periodthe electric motor 420 is used to maintain scheduled power and speeduntil steady state Rankine cycle conditions are achieved.

During thermal engine activation air enters turbocompressor 201 throughduct 204 and is raised to the design discharge pressure. The air thenexits through duct 205 into intercooler 206 where the heat ofcompression is removed by external cooling means 207 (i.e. air, water,Freon, etc.). Condensed water vapor is tapped-off by drain 208. Afterthe air exits intercooler 206 through duct 209 at a temperature equal tothe compressor inlet, it enters compressor 211 and is raised to thedesign discharge pressure. The air then exits through duct 212 intointercooler 213 and is again cooled to the inlet temperature of thecompressor 201. This compression/cooling cycle is repeated as the airexits intercooler 213 through duct 214, enters compressor 215, thenexits through duct 216, enters intercooler 217 and exits through duct218 to complete the air pressurization.

The high pressure ambient temperature air then enters scrubber 219 wheregases and fluids that are subject to freezing during the liquefactionprocess are removed (i.e. carbon dioxide, water vapor and oil). Carbondioxide exits through duct 221 a and is processed and stored inreservoir 221 b. Oil is drained through duct 222 a and stored inreservoir 222 b. Water vapor is drained through duct 223 and dischargedoverboard.

The dry air then exits through duct 224 and enters the heat exchanger240 where the air is cooled by returning gaseous nitrogen. It then exitsthrough duct 225 and enters turboexpander 226 where the air temperatureis further reduced to near liquid air temperature prior to exitingthrough duct 227 and enters the rectifier 260. The air exits from therectifier heat exchanger 228 through duct 229 at liquid air temperatureand enters the rectifier's lower column plates where oxygen/nitrogenseparation is initiated. Liquid with 40% oxygen exits through duct 231and enters the upper rectifier column where a higher percentage oxygenconcentration is generated. Liquid nitrogen at 96% purity isrecirculated from the lower rectifier column to the upper column bymeans of duct 232. Gaseous nitrogen at 99% purity (1% argon) exitsthrough duct 233 and enters the heat exchanger 240 where cooling theincoming dry air is performed prior to discharging through duct 234 tothe atmosphere at near ambient temperature and pressure. Gaseous oxygenor liquid oxygen at 95% purity (5% argon) exits through duct 235 andenters the turboexpander compressor 236 where the oxygen is pressurizedto the design pressure. The high pressure oxygen then exits through duct237 and enters the gas generator 270 through duct 238.

Fuel, i.e. methane, propane, purified natural gas and light alcoholssuch as methanol and ethanol, exits the fuel supply tank 239 throughduct 241 and enters the compressor 242 of turboexpander 250 and israised to the design discharge pressure. The pressurized fuel then exitsthrough duct 243 and enters the gas generator 270 through duct 244 whereit mixes with the incoming oxygen at stoichiometric mixture ratio toachieve complete combustion and maximum hot gas temperature(approximately 6500° R). The products of combustion of these reactantsresult in a high purity steam, carbon dioxide gas and a small amount ofgaseous argon (4%).

Following complete combustion of the high temperature gases,recirculating water is injected into the gas generator through line 245and dilutes the high temperature gases to a lower temperature drive gasacceptable to the dynamic turbine 247 (approximately 2000° R). The drivegas then exits the gas generator 270 through duct 246 and enters theturbine 247 of turbocompressor 220, where the gas expands and powers theair compressor 215 and the carbon dioxide compressor 273. The gas thenexits through duct 248 and enters reheater 280 where the heat extracteddue to the turbine 247 work is replenished. This heat is derived fromthe combustion of added fuel through duct 249 and added oxygen throughduct 251 into reheater 280.

The reheated gas then exits through duct 252 and enters turbine 253 ofturbocompressor 210 and expands to lower pressure. The power produced bythese expanding gases drive the alternator 400 and compressor 211, thenexhaust through duct 254 and enter reheater 290. The heat extracted fromthe gases resulting in the turbine work is replenished with the heat ofcombustion from added fuel through duct 255 and oxygen through duct 256.

The reheated gas then exits through duct 257, enters turbine 258 ofturbocompressor 200 and drives compressor 201 and power transmission230. The turbine exhaust gas then exits through duct 259 and enterswater heater 300 where the residual heat of the turbine 258 exhaust isused to preheat the water that is being recirculated to the gasgenerator 270. The gas then exits through duct 261, enters the condenser310 near or below atmospheric pressure, where condensation of the steaminto water and separation of the carbon dioxide gas occurs.

The condensed water exits through line 262, enters the pump 263 wherethe pressure is raised to the supply level of the gas generator 270. Amajor portion of the discharge water from pump 263 exits through line264, enters the water heater 300 where heat is absorbed from the turbineexhaust gas and then exists through line 245 for delivery to the gasgenerator 270. The remaining water from the discharge of pump 263 exitsthrough line 265 and is sprayed through nozzles 266 into radiator 330for evaporative cooling. Coolant for the condenser gas is recirculatedby pump 267 to the radiator 330 through line 268, where heat is rejectedto atmospheric air being pumped by fan 269.

The gaseous carbon dioxide, remaining from the condensation of steam,exits through duct 271 and enters compressor 273 of turbocompressor 220and is compressed to slightly above atmospheric pressure (when condenserpressure is below atmospheric) and discharged through duct 274 intostorage tank 275. The compressed carbon dioxide can be converted into aliquid or solid state for periodic removal, or the gas can be dischargedinto the atmosphere as local environmental laws permit.

The seventh embodiment of this invention, illustrated in FIG. 10,includes the liquefaction system of the previous embodiments bututilizes the intermittent but spontaneous combustion process of the Ottocycle as the thermal power engine. This embodiment eliminates the needfor the steam condenser and the recirculating water system.

The Otto cycle steam or steam/CO2 thermal engine consists of, inaddition to the liquefaction system previously described, a premixer 430where oxygen from duct 35, fuel from duct 41 and recirculating steam orsteam/CO2 from duct 301 are premixed in the approximate ratio of 20%, 5%and 75% by weight respectively. These premixed gases are then directedto the reciprocating pistons 302 through duct 303 and ducts 304 wherethey are compressed and ignited with a spark ignition system identicalto current Otto cycle engines. After the power stroke, the steam orsteam/CO2 gases are discharged to the dynamic turbine 48 through ducts305, 306 and then into duct 47. Some of the discharge gases are directedback to the premixer 430 through duct 301. The exhaust gases from thedynamic turbine 48 are then discharged to the atmosphere through duct307.

The eighth embodiment of this invention, illustrated in FIG. 11, issimilar to the seventh embodiment, except a Diesel power cycle is used.In this system a premixer 440 mixes the oxygen from duct 35 with steamor steam/CO2 from duct 308, at an approximate mixture ratio of 23% and77% by weight respectively, and discharges the gaseous mixture to thereciprocating pistons 309 through duct 311 and ducts 312 where themixture is compressed to a high pre-ignition temperature. The highpressure fuel, at approximately 5% of the total weight of the gasmixture in the piston cylinder, is injected through ducts 313 and burnsat approximately constant pressure. If necessary, an ignition device islocated within the combustion cylinder. The hot gases then rapidlyexpand as the piston moves to the bottom of its power stroke. Thesteam/CO2 gases are then discharged into ducts 313 and delivered to thedynamic turbine 48 through duct 47. Some of the discharged gases arediverted to the premixer 440 through the duct 308. The exhaust gasesfrom the dynamic turbine 48 are then discharged into the atmospherethrough duct 307.

FIG. 12 depicts a basic low-polluting engine 500 which conceptuallyrepresents many of the above-described first eight embodiments in a moresimplified manner. Rather than identifying specific machinery, FIG. 12depicts steps in the overall power production cycle. Additionally, theengine 500 of FIG. 12 replaces the rectifier and other liquefactionequipment of embodiments 1-8 with a more generalized air separationplant 530. Details of various different embodiments of this airseparation plant 530 are provided in FIGS. 15 and 16 and described indetail herein below.

The basic low-polluting engine 500 operates in the following manner. Airfrom a surrounding environment enters through an air inlet 510 into anair compressor 520. The air compressor 520 elevates the air enteringthrough the air inlet 510 and directs the compressed air to the airseparation plant 530. Various different air separation techniques can beutilized by the air separation plant 530 so that enriched nitrogen gasesexit the air separation plant 530 through an enriched nitrogen gasoutlet 532 and enriched oxygen gases exit the air separation plant 530through an enriched oxygen gases outlet 534. The enriched nitrogen gasesoutlet 532 typically returns back into the surrounding environment. Theenriched oxygen gases outlet 534 leads to the combustion device 550.

In the combustion device 550, the enriched oxygen gases from the airseparation plant 530 are combined with the hydrogen containing fuel froma fuel supply 540 and combustion is initiated within the combustiondevice 550. A water or carbon dioxide diluent is added into thecombustion device to decrease a temperature of the products ofcombustion within the combustion device 550 and to increase a mass flowrate for a steam or steam and carbon dioxide working fluid exiting thecombustion device 550.

This working fluid is then directed into an expander 560, such as aturbine. The turbine is coupled through a power transfer coupling 562 tothe air compressor 520 to drive the air compressor 520. FIG. 12 shows arotating shaft as one type of mechanical power transfer coupling 562.Another way to power the air compressor 520 is to generate electricityby means of the power absorber 570 and use part of the generatedelectricity to drive an electric motor which in turn powers the aircompressor 520. The expander 560 also is coupled through a powertransfer coupling 564 to a power absorber 570 such as an electricgenerator or a power transmission for a vehicle. The expander 560 isalso coupled through a power transfer coupling 566 to the air separationplant 530 to drive machinery within the air separation plant 530.

The working fluid is then discharged from the expander 560 through adischarge 572. The discharge 572 leads to a condenser 580. The condenserhas coolant passing through a coolant flow path 592 which causes waterportions of the working fluid entering the condenser 580 to becondensed. A water and carbon dioxide outlet 590 is provided for excesswater or water and carbon dioxide mixture from the condenser. A water orwater and carbon dioxide diluent path is also provided out of thecondenser 580 for returning water or water and carbon dioxide diluentback to the combustion device 550.

As should be readily apparent, the air compressor 520 is generallyanalogous to the turbocompressor 10 of the first embodiment. The airseparation plant 530 is generally analogous to the rectifier 60 of thefirst embodiment. The fuel supply 540 is generally analogous to the fuelsupply tank 37 of the first embodiment. The combustion device 550 isgenerally analogous to the gas generator 70 of the first embodiment. Theexpander 560 is generally analogous to the reciprocating cylinders 44,46 of the reciprocating engine 20 of the first embodiment. The powerabsorber 570 is generally analogous to the power transmission 30 of thefirst embodiment and the condenser 580 is generally analogous to thecondenser 80 of the first embodiment. Hence, the basic low-pollutingengine schematic of FIG. 12 represented by reference numeral 500 merelyprovides an overall depiction of the power production cycle of thisinvention. While a specific analogy has been drawn between this basiclow-polluting engine 500 and the first embodiment, shown in FIG. 1,similar analogies can be drawn to the other embodiments of thisinvention.

With particular reference to FIG. 13, details of a basic low-pollutingengine 600 featuring regeneration is provided. The low-polluting enginefeaturing regeneration 600 depicted in FIG. 13 is identical to the basiclow-polluting engine 500 of FIG. 12 except that handling of the workingfluid upon discharge from the expander 660 has been altered to featureregeneration. Specifically, the low-polluting engine featuringregeneration 600 includes an air inlet 610, air compressor 620, airseparation plant 630, fuel supply 640, combustion device 650, expander660 and power absorber 670 arranged similarly to the components 510,520, 530, 540, 550, 560, 570 of the basic low-polluting engine 500 shownin FIG. 12.

In contrast, the low-polluting engine featuring regeneration 600 directsthe working fluid through a discharge 672 which leads to a regenerator674. The working fluid exits the regenerator 674 through a regeneratoroutlet 676. The regenerator outlet 676 leads to a condenser 680. Withinthe condenser 680, the working fluid is cooled by action of a coolantflowing along a coolant flow path 682 to be separated into carbondioxide and water. The carbon dioxide exits the condenser 680 through acarbon dioxide outlet 684 and the water exits the condenser 680 throughthe water outlet 686. The water outlet 686 leads to a feed water pump688. Excess water is discharged from the engine 600 at a water excessoutlet 690. Other portions of the water are directed along a regeneratorwater flow path 692 through the regenerator 674 where the water ispreheated. The water or steam leaves the regenerator 674 along a waterdiluent path 694 leading back to the combustion device 650.

The carbon dioxide outlet 684 from the condenser 680 also leads into theregenerator 674 for preheating of the carbon dioxide. The carbon dioxideleaves the regenerator along a regenerator carbon dioxide flow 696 whichleads to a carbon dioxide compressor 697. The carbon dioxide compressor697 in turn leads to a carbon dioxide excess outlet 698 where excesscarbon dioxide is removed from the engine 600. If desired, a portion ofthe carbon dioxide can be directed along a carbon dioxide diluent path699 back to the combustion device 650 for use as a diluent within thecombustion device 650.

With particular reference to FIG. 14, a basic low-polluting engine 700with bottoming cycle is provided. As with the low-polluting enginefeaturing regeneration 600 of FIG. 13, portions of the low-pollutingengine featuring a bottoming cycle 700 are similar to the basiclow-polluting engine 500 of FIG. 12 up until discharge of the workingfluid from the expander 560. Hence, the low polluting engine featuring abottoming cycle 700 includes an air inlet 710, air compressor 720, airseparation plant 730, fuel supply 740, combustion device 750, expander760 and power absorber 770 having corresponding components in the engine500 of FIG. 12.

The working fluid is discharged from the expander 760 through adischarge 772 leading to a Heat Recovery Steam Generator(HRSG)/condenser 774. The working fluid is condensed and a water outlet775 directs water from the condenser 774 and a carbon dioxide outlet 776directs carbon dioxide from the condenser 774. The carbon dioxide outlet776 leads to a carbon dioxide compressor 777, a carbon dioxide excessoutlet 778 and carbon dioxide diluent path 779 leading back to thecombustion device 750.

The water outlet 775 leads to a feed water pump 780 which in turn leadsto a water excess outlet 781 and a water regeneration path 782 where thewater is regenerated within a bottoming regenerator 787. The water exitsthe bottoming regenerator 787 along a water diluent path 783 leadingback to the combustion device 750.

The HRSG/condenser 774 and regenerator 787 are driven by a bottomingcycle including a bottoming cycle boiler 784 which boils water in thebottoming cycle from the discharge working fluid from the discharge 772and entering the HRSG/condenser 774. The topping cycle also includes abottoming turbine 786 and a bottoming regenerator 787 which cools steamexiting the steam turbine 786 and heats water entering the water diluentpath 783. The bottoming cycle also includes a bottoming condenser 788cooled by a coolant within a coolant line 789. Hence, the working fluidsuch as water within the bottoming cycle passes from the condenser 788to the boiler 784 where the working fluid is heated and turned into agas. Note that the HRSG/condenser 774 and boiler 784 are integratedtogether but that only heat exchange is allowed, not mixing. Thebottoming cycle working fluid then passes through the turbine 786 forproduction of power which can be directed to the power absorber 770 orother components of the low-polluting engine featuring a bottoming cycle700. The working fluid then exits the turbine 786 and is cooled in theregenerator 787 before returning to the condenser 788.

The air separation plants 530, 630, 730 of FIGS. 12-14 can be any of avariety of different apparatuses or systems which are capable ofremoving at least a portion of the nitrogen from air. For instance, andspecifically discussed above with respect to the first through eighthembodiments of FIGS. 1-11, the air separation plant 530, 630, 730 caninclude a rectifier such as the rectifier 60 of FIG. 1 or otherliquefaction equipment which separate nitrogen from the air byliquefaction.

However, liquefaction processes are not the only processes that canremove at least a portion of nitrogen from air. Several other processesare available to achieve this goal. These processes, which are describedin detail below, can be substituted for the cryogenic liquefactionprocess described in detail hereinabove. One alternative techniqueavailable for use in the air separation plant 530, 630, 730 is apressure swing adsorption plant 800 (FIG. 15). The pressure swingadsorption process, also called vacuum pressure swing adsorption, usesmaterials which are capable of adsorption and desorption of oxygen ornitrogen such as, for example, synthetic zeolites. The vacuum pressureswing adsorption process can be used to separate oxygen and nitrogenfrom air.

The process typically employs two beds that go through swings inpressure from above atmospheric to below atmospheric pressure. Each bedcycles sequentially from adsorption to desorption and regeneration andback to adsorption. The two beds operate in a staggered arrangement inwhich one bed is adsorbing while the other bed is regenerating. Thus thebeds alternately produce a gaseous product of high oxygen content. Withthis process, a gaseous mixture can be produced with a wide range ofoxygen purities. As an example, oxygen purities ranging from 90% to 94%are used in many industrial applications and can be successfullyproduced with commercially available vacuum pressure swing adsorptionprocesses such as those produced by Praxair, Inc. with worldheadquarters located at 39 Old Ridgebury Road, Danbury, Conn.06810-5113.

With particular reference to FIG. 15, a layout of a typical pressureswing adsorption plant 800 is shown. Initially, the air inlet 510 andfeed compressor 520 are provided analogous to the air inlet 510 and aircompressor 520 of the basic low-polluting engine schematic 500 shown inFIG. 12. Preferably, a filter 515 is interposed between the air inletand the feed compressor to filter particulates out of the air inletstream. The compressed air discharged from the feed compressor 520 isdirected to a first inlet line 810 passing through a first inlet linevalve 815 and into a first enclosure 820.

The first enclosure 820 is provided with an appropriate material capableof adsorption and desorption of oxygen or nitrogen. One material that isused in these applications is zeolite. Two outlets are provided from thefirst enclosure 820 including a first oxygen outlet 830 coupled to thefirst enclosure 820 through a first valve 832 and a first nitrogenoutlet 835 coupled to the first enclosure 820 through a first nitrogenvalve 836. The first nitrogen outlet 835 leads to a nitrogen compressor837 which raises the gases in the first nitrogen outlet 835 back toatmospheric pressure for discharge through nitrogen discharge 839. Infact, the first nitrogen outlet 835 and first oxygen outlet 830 do notcontain pure oxygen or nitrogen but rather merely gases which areenriched in content with oxygen or nitrogen.

The first oxygen outlet 830 leads to a surge tank 870 with a valve 875beyond the surge tank 870 and leading to an oxygen supply line 880. Inparallel with the first enclosure 820, a second enclosure 850 isprovided. The second enclosure 850 is similarly loaded with anappropriate material capable of adsorption and desorption of oxygen ornitrogen. A second inlet line 840 leads from the feed compressor 520through a second inlet line valve 845 and into the second enclosure 850.A second oxygen outlet 860 leads out of the second enclosure 850 and onto the surge tank 870 through a second oxygen outlet valve 862. A secondnitrogen outlet 865 also leads out of the second enclosure 850 through asecond nitrogen outlet valve 866 and on to the compressor 837. A cyclecontroller 890 controls the opening and closing of the various valves815, 832, 836, 845, 862, 866 and 875.

One typical operation sequence of the pressure swing adsorption plant800 is as follows. Initially, all of the valves are closed except forthe first nitrogen valve 836 and the nitrogen compressor 837 is used toreduce pressure in the first enclosure 820 to below atmosphericpressure. The first nitrogen valve 836 is then closed. Next, the firstinlet valve 815 is opened. With the first inlet line valve 815 open andall other valves closed, the feed compressor directs air into the firstenclosure 820.

As pressure builds up within the first enclosure 820, the materialwithin the first enclosure 820 is caused to adsorb different moleculeswithin the air in a discriminate fashion. For instance, the material canbe selected to adsorb nitrogen at elevated pressure. At reducedpressure, the adsorption effect reverses to desorption.

In essence, if the material adsorbs nitrogen at pressures elevated aboveatmospheric pressure and desorbs nitrogen at pressures below atmosphericpressure, the various valves 815, 832, 836 and 875 are sequentiallyoperated so that the first enclosure 820 has an elevated pressure andadsorbs nitrogen before the remaining enriched oxygen air is allowed tofreely flow out of the first enclosure 820 along the first oxygen outlet830. When the oxygen enclosure 820 has a pressure below atmosphericpressure, the material within the first enclosure 820 is desorbing thenitrogen while the first nitrogen outlet valve 836 is open. In this way,when nitrogen is being adsorbed, the remaining air within the firstenclosure 820 is enriched in oxygen and is directed to the first oxygenoutlet 830 and when the material within the enclosure 820 is desorbingthe nitrogen, the nitrogen enriched gases within the first enclosure 820are allowed to flow into the first nitrogen outlet 835 and to thenitrogen discharge 839.

The zeolite material within the enclosure 820 benefits from someresidence time to adsorb as much nitrogen (or oxygen) as desired. Duringthis time no oxygen rich or nitrogen rich gases flow to the oxygensupply line 880 or the nitrogen discharge 839. Hence, it is beneficialto use a second enclosure 850 similar to the first enclosure 820 whilethe valves 815, 832 and 836 are all closed and the zeolite material inthe first enclosure 820 is adsorbing nitrogen (or oxygen).

Specifically the valves 845, 862 and 866 are sequentially opened andclosed to cause the second enclosure 850 to operate in a manner similarto that outlined with reference to the first enclosure 820 above. Whenthe material within the second enclosure 850 is adsorbing nitrogen (oroxygen) the process is reversed so that the first enclosure 820, havinghad its zeolite material appropriately desorbed, is brought back on linefor repetition of the alternating pattern of use between the firstenclosure 820 and the second enclosure 850. As should be apparent,additional enclosures besides the first enclosure 820 and secondenclosure 850 could be utilized if the adsorbing material requires moreresidence time or to increase the overall throughput of oxygen enrichedgases from the air. Over time, the material within the first enclosure820 which adsorbs and desorbs the oxygen or nitrogen tends to lose itseffectiveness. The material can be regenerated, if it is in the form ofa synthetic zeolite, by application of heat or other regeneration means.Accordingly, when the material within the first enclosure 820 begins tolose its effectiveness, such a heat treatment can be performed or thezeolite material replaced. Should the adsorbing material be configuredto adsorb and desorb oxygen rather than nitrogen, the above describedoperation of the pressure swing adsorption plant 800 would be adjustedto provide the desired separation of oxygen from nitrogen.

With particular reference to FIG. 16, details of an alternativeapparatus and system for use within the air separation plants 530, 630,730 is provided. In such membrane-based air separation systems 900 theseparation of air into its components is achieved by passing an air feedstream under pressure over a membrane. The pressure gradient across themembrane causes the most permeable component to pass through themembrane more rapidly than other components, thereby creating a productstream that is enriched in this component while the feed stream isdepleted in this component.

The transport of the air through a membrane can follow several physicalprocesses. As an example, these processes could be: 1) Knudsen flowseparation which is based on molecular weight differences between thegases; 2) Ultramicroporous molecular sieving separation; and 3)Solution-diffusion separation which is based both on solubility andmobility factors. In the case of a solution-diffusion process the airfirst dissolves in a polymer, then diffuses through its thickness andthen evaporates from the other side into the product stream.

Several types of membranes are available for this process, each havingspecific advantages in particular situations. For example, celluloseacetate membranes exhibit good separation factors for oxygen andnitrogen, but have low flux rates. Thin film composite membranes placedover microporous polysulfone exhibits lower separation factors thancellulose acetate, but have a higher flux at the same pressuredifferential. Repeating the process in a series configuration canincrease the oxygen concentration in the product stream. For example,one industrial membrane, in two passes, may enrich the oxygen content ofair to about 50%.

The above described membrane processes operate at a temperature that isnear ambient temperature. A higher-than-ambient temperature may arise asa result of a possible temperature rise resulting from pressurization ofthe air feed stream to create a pressure difference across the membrane.

Still another membrane separation process uses an electroceramicmembrane. Electroceramics are ionic solid solutions that permit movementof ions. To become appreciably mobile, the oxide ion, because of itssize and charge, requires a high temperature (about 800° F.) to overcomethe solid oxide lattice energy. The electroceramic membrane processintegrates well with the production of power described in this inventionbecause the power generating process produces waste heat that can beused to generate the required operating temperature of the membrane. Forinstance, and with reference to FIG. 12, the expander 560 and gasgenerator 550 can be configured such that the working fluid exiting theexpander 560 at the discharge 572 has a temperature at or above 800° F.The working fluid can then be routed to a heat exchanger which heats theelectroceramic membranes to 800° F. for use in the air developmentsystem 530.

The oxygen ions move through the lattice because of a gradient inpressure across the membrane. On the high oxygen partial pressure sideof the membrane, oxygen is reduced when it receives four electrons andoccupies two vacancies. At the low oxygen partial pressure side,vacancies are created by the reverse reaction. Oxide ions at the lowpartial pressure side can be removed by liberation of oxygen. The rateof diffusion through the membrane is determined by ion mobility. Thismobility is a characteristic of a particular material, and is dependenton the size, charge and geometry of the cations in the lattice. Apossible material for formation of the electroceramic membrane is yttriastabilized zirconia.

With particular reference to FIG. 16, one arrangement for the membranebased air separation system for use in the air separation plants 530,630, 730 is depicted by reference numeral 900. In this embodiment forthe air separation plant, an air inlet 510 and feed compressor 520 areprovided similar to the air inlet 510 and feed compressor 520 disclosedin FIG. 12 with regard to the basic low-polluting engine 500. Thecompressed air is then directed to a junction 910 where return flowsfrom various membrane chambers return for reprocessing and are combinedtogether within the junction 910. A junction outlet 915 provides theonly outlet from the junction 910. The junction outlet 915 leads to afirst membrane enclosure 920.

The first membrane enclosure 920 is preferably an enclosure which has aninlet and a membrane dividing the enclosure into two regions. Twooutlets are provided in the enclosure. One of the outlets is on the sameside of the membrane as the inlet and the other outlet is located on aside of the membrane opposite the inlet. If the membrane is of a typewhich allows oxygen to pass more readily there through than nitrogen, anoxygen rich outlet 924 is located on the downstream side of the membraneand a nitrogen rich outlet 926 is located on a same side of the membraneas the inlet 915. If the membrane allows nitrogen to pass more readilythere through, the arrangement of the outlets is reversed.

The junction outlet 915 passes into the first membrane enclosure 920through the inlet in the first membrane enclosure 920. Because oxygenflows more readily through the membrane within the first membraneenclosure 920, gases flowing through the oxygen rich outlet 924 have anincreased percentage of oxygen with respect to standard atmosphericoxygen percentages and the nitrogen rich outlet 926 has a nitrogencontent which is greater than that of standard atmospheric conditions.

The oxygen rich outlet 924 leads to a second membrane enclosure 930where it enters the second membrane enclosure 930 through an oxygen richinlet 932. The second membrane enclosure 930 is arranged similarly tothe first membrane enclosure 920. Hence, a membrane is provided withinthe second membrane enclosure 930 and two outlets are provided includingan oxygen super rich outlet 934 on a side of the membrane opposite theoxygen rich inlet 932 and a second outlet 938 located on a common sideof the membrane within the second membrane enclosure 930 as the oxygenrich inlet 932.

The oxygen super rich outlet 934 leads to an oxygen supply 936 for usewithin one of the engines 500, 600, 700 discussed above. The gasesflowing through the second outlet 938 typically have oxygen and nitrogencontents matching that of standard atmospheric conditions butmaintaining an elevated pressure. The second outlet 938 returns back tothe junction 910 for combining with air exiting the feed compressor 520and for repassing through the first membrane enclosure 920 as discussedabove.

The nitrogen rich outlet 926 exiting the first membrane enclosure 920 ispassed to a third membrane enclosure 940 where it enters the thirdmembrane enclosure 940 through a nitrogen rich inlet 942. The thirdmembrane enclosure 940 is similarly arranged to the first membraneenclosure 920 and second membrane enclosure 930 such that a membrane islocated within the third membrane enclosure 940 and two outlets areprovided from the third membrane enclosure 940. One of the outlets is anitrogen super rich outlet 944 on a side of the membrane within thethird membrane enclosure 940 similar to that of the nitrogen rich inlet942. The nitrogen super rich outlet 944 can lead to a surroundingatmosphere or be used for processes where a high nitrogen content gas isdesirable.

A third permeate return 948 provides an outlet from the third membraneenclosure 940 which is on a side of the membrane within the thirdmembrane enclosure 940 opposite the location of the nitrogen rich inlet942. The third permeate return 948 leads back to the junction 910 forreprocessing of the still pressurized air exiting the third membraneenclosure 940 through the third permeate return 948. This air passingthrough the third permeate return 948 is typically similar in content tothe second permeate return 938 and the air exiting the feed compressor520.

While many different types of membranes can be utilized within the firstmembrane enclosure 920, second membrane enclosure 930 and third membraneenclosure 940, the type of membrane would typically not alter thegeneral arrangement of the membrane enclosures 920, 930, 940 andconduits for directing gases between the various permeates 920, 930, 940and other components of the membrane based air separation plant 900 ofFIG. 16.

While various different techniques have been disclosed for separation ofnitrogen and oxygen from air, this description is not provided toidentify every possible air separation process or apparatus. Forexample, economic and other consideration may make application ofcombinations of the above described processes advantageous. Rather,these examples are presented to indicate that several separationprocesses are available to accomplish the goal of enriching the oxygencontent of air supplied to a combustion device and decreasing acorresponding nitrogen content of the air supply to a combustion device.By reducing an amount of nitrogen passing into a combustion device suchas these combustion devices 550, 650, 750, an amount of nitrogen oxidesproduced as products of combustion within the combustion device 550,650, 750 is reduced and low-pollution combustion based power productionresults.

FIG. 17 depicts a preferred embodiment of this invention which not onlyemits low or zero pollutants but additionally isolates and conditionsCO2 for sequestering into deep underground or undersea locations. Whilethis preferred embodiment shows a specific arrangement of componentsincluding combustors, turbines, condensers and compressors, the CO2sequestration portion of this system could readily be adapted for usewith many of the above-identified embodiments. Particularly, each of theembodiments identified above which utilizes a hydrogen and carboncontaining fuel, rather than merely hydrogen as the fuel, includescarbon dioxide as one of the combustion products. The CO2 isolation andsequestration portion of the preferred embodiment of FIG. 17 can beadapted to work with each of these hydrocarbon and carbon containingfuel embodiments to provide an additional benefit to these embodiments.

Specifically, and with particular reference to FIG. 17 the preferredembodiment of a hydrocarbon combustion power generation system with CO2sequestration 1,000 is described. For clarity, reference numeralsdivisible by 10 are provided for various components of the system 1,000and other reference numerals are provided for various different flowpathways of the system 1,000. The various different flow pathways couldbe in the form of hollow rigid or flexible tubing with appropriateinsulation and with appropriate wall thicknesses for pressure handlingcapability depending on the material temperature and pressure conditionstherein.

Initially, air is drawn from the atmosphere or some other source of airand passes along line 1,002 for entry into the air separation plant1,010. Before the air passes into the air separation plant 1,010, theline 1,002 would typically pass through a filter to remove particulates,a drier to remove moisture and a precooler 1,005 to decrease thetemperature of the air. A line 1,004 exits the precooler 1,005 andtransports the air into the air separation plant 1,010. In thispreferred system 1,000 the air separation plant 1,010 utilizesliquefaction techniques to separate oxygen in the air from nitrogen inthe air. Hence, significant cooling of the air is necessary and theprecooler 1,005 beneficially assists in this cooling process. However,other air separation techniques are known, as identified above. If suchnon-liquefaction air separation techniques are utilized, the precooler1,005 would not be necessary.

Regardless of the air separation technique utilized by the airseparation plant 1,010, two outlets for the air separation plant 1,010are provided including an oxygen outlet into line 1,012 and a nitrogenoutlet into line 1,011. If the air separation plant 1,010 only removes aportion of the nitrogen in the air, the oxygen outlet will in fact befor oxygen enriched air rather than pure oxygen. Line 1,011 can directthe nitrogen which, when liquefaction is used in the air separationplant 1,010, is below a temperature of air entering the air separationplant 1,010 along line 1,002. Hence, line 1,011 directs nitrogen to theprecooler 1,005 for cooling of the incoming air in line 1,002. Thenitrogen then exits the precooler 1,005 along line 1,013 and is thenutilized to cool carbon dioxide (CO2) generated as combustion productsof the system 1,000 as discussed in detail below. The nitrogen in line1,013, after being utilized to cool the CO2, can be released into theatmosphere along line 1,015. Because nitrogen constitutes overthree-quarters of air no contamination of the atmosphere results fromdischarge of the nitrogen into the atmosphere from line 1,015.

The oxygen exiting the air separation plant 1,010 passes along line1,012 and is fed to oxygen feed lines 1,014 and 1,016. The oxygen feedline 1,016 passes into a combustor 1,020. The combustor 1,020additionally includes a fuel feed line 1,018 leading from a source offuel into the combustor 1,020. While various different hydrocarbon fuelscan be utilized in the combustor 1,020, including simple hydrocarbonsand light alcohols, the fuel is preferably methane. The combustor 1,020additionally has water fed into the combustor 1,020 along line 1,102 toprovide cooling within the combustor 1,020 and to increase a mass flowrate of combustion products exiting the combustor 1,020 along line1,022. Preferably, the combustor 1,020 includes an ignition device andis constructed in a manner to operate at a high temperature and highpressure. Specifically, the combustor could operate at a pressure of1,200 psia and 1,600° F., if near term existing technology componentsare utilized and up to 3,200 psia and 3,200° F. if known hardwaredesigns, which are not yet readily available but are anticipated to beavailable in the long term, are utilized.

One such combustor which exhibits the basic characteristics necessaryfor combustion of the hydrocarbon fuel with the oxygen and which allowsfor water injection and mixing with the combustion products is describedin U.S. Pat. No. 5,709,077 and provided by Clean Energy Systems, Inc. ofSacramento, Calif. The contents of this patent are hereby incorporatedby reference into this description.

The combustion products exit the combustor 1,020 along line 1,022 andare then directed to a high pressure turbine 1,030. While the highpressure turbine 1,030 is preferred, other expansion devices such aspistons could similarly be utilized. The high pressure turbine 1,030 ispreferably similar to that which has been demonstrated which featurehigh temperature, high pressure materials utilized as necessary tohandle the temperatures and pressures of the combustion products in theranges discussed above. One such turbine is manufactured by SolarTurbines, Inc. of San Diego, Calif.

The high pressure turbine 1,030 discharges the combustion products alongline 1,032 which leads to the reheater 1,040. The high pressure turbine1,030 also discharges power to shaft 1,034 which can either be coupleddirectly to a generator 1,070, be utilized to provide power to anotherpower absorption device such as a propulsion system of a vehicle or arotational power output shaft for a system requiring such rotationalpower, or can be coupled to other turbines or compressors of this system1,000.

The combustion products passing along line 1,032 enter the reheater1,040 along with oxygen from line 1,014 and fuel such as methane fromfuel feed line 1,036. The reheater 1,040 is similar in configuration tothe combustor 1,020 except that the combustion products including bothH2O and CO2 are directed into the reheater rather than merely H2O aswith the combustor 1,020 and the pressure and temperature of thecombustion products entering the reheater 1,040 are greater than thetemperature of the H2O entering the combustor 1,020 from the feed waterline 1,102.

The reheater 1,040 combusts the fuel from the fuel line 1,036 with theoxygen from line 1,014 to produce additional combustion productsincluding H2O and CO2. These combustion products generated within thereheater are mixed with the combustion products entering the reheaterfrom line 1,032 and originally generated within the combustor 1,020.Preferably, the combined combustion products exit the reheater 1,040along line 1,042 and have a pressure of 120 psia and a temperature of2,600° F. if near term available components are used in the system 1,000and 220 psia and 3,200° F. if components available in the long term areutilized in the system 1,000. The intermediate pressure turbine 1,050typically features turbine blade cooling and high temperature materialssimilar to the technology developed by the gas turbine industry, i.e.General Electric, Solar Turbines, etc.

These combined combustion products including H2O and CO2 pass along line1,042 and into intermediate pressure turbine 1,050. After expansionwithin the intermediate pressure turbine 1,050 the combustion productsexit the intermediate pressure turbine 1,050 through turbine discharge1,052. At the turbine discharge 1,052 the combustion products preferablyhave a pressure of 12 psia and a temperature of 1,400° F. if near termavailable components are used in the system 1,000 and 15 psia and 2,000°F. if long term available components are used in the system 1,000.

The intermediate pressure turbine 1,050 is additionally coupled to apower output shaft 1,054 which can either be coupled directly to thegenerator 1,070, or utilized to drive other components within the system1,000 or provide rotational power output from the system 1,000.Preferably, the power output shaft 1,034 from the high pressure turbine1,030 and the power output shaft 1,054 from the intermediate pressureturbine 1,050 are joined together and coupled to the generator 1,070.

The combustion products exiting the intermediate pressure turbine 1,050along turbine discharge line 1,052 pass through a feed water preheater1,100 which provides preheating for the H2O passing along line 1,102 andentering the combustor 1,020. After the combustion products pass throughthe feed water preheater 1,100, the combustion products pass along line1,056 into the low pressure turbine 1,060. The combustion productspreferably nearly maintain their pressure through the feed waterpreheater 1,100 but decrease in temperature, preferably by approximately200° F. The combustion products then enter the low pressure turbine1,060 where the combustion products are further expanded and dischargedalong line 1,062.

The low pressure turbine 1,060 is preferably coupled to the generator1,070 through a power output shaft 1,064 which is in turn coupled topower output shaft 1,034 and 1,054. The generator 1,070 can eitherprovide rotational shaft power to rotational equipment such ascompressors and other components of the system 1,000 requiringrotational shaft power or can generate electricity and utilize thatelectricity to power various components of the system 1,000. Forinstance, power from the generator 1,070 can be directed along line1,072 to the air separation plant 1,010 to provide power to the airseparation plant 1,010 as necessary to separate the oxygen from thenitrogen. Power can be transmitted from the generator 1,070 along line1,074 to a CO2 compressor 1,110 discussed in detail below or along line1,076 to a CO2 pump 1,140 discussed in detail below or can be outputtedfrom the system along line 1,078 for delivery as electric power to apower grid or as electric power or shaft power to provide power in anymanner desired.

The combustion products exiting the low pressure turbine 1,060 alongline 1,062 preferably include only H2O and CO2. Alternatively, if theair separation plant 1,010 does not completely separate oxygen fromother air constituents, or contaminates are introduced into thecombustion products from the fuel, some additional constituents may bepresent within the combustion products. If such additional constituentsare present, they can be removed from the H2O and CO2 combustionproducts or handled along with the H2O or CO2 combustion products.

The combustion products pass along line 1,062 into the condenser 1,080.The condenser 1,080 provides one form of a combustion productsseparator. The condenser 1,080 is cooled with a coolant such as H2Opassing through the condenser 1,080 along line 1,082. This coolantmaintains conditions within the condenser 1,080 at a temperature andpressure at which most of the H2O condenses into a liquid phase and CO2remains in a gaseous phase. Preferably, these conditions within thecondenser are 1.5-2.0 psia and 80-100° F.

A condenser liquid outlet leads to line 1,084 which in turn leads to afeed water pump 1,090. The feed water pump 1,090 increases a pressure ofthe H2O exiting the condenser 1,080 along line 1,084 and discharges theelevated pressure H2O along line 1,092. Excess H2O can be removed fromline 1,092 along line 1,094. Remaining H2O passes along line 1,096 tothe feed water preheater 1,100. The H2O then exits the feed waterpreheater 1,100 along line 1,102 for return to the combustor 1,020 asdiscussed above.

The condenser 1,080 includes a gaseous products of combustion outletwhich leads to a line 1,086. The gaseous products of combustion exitingthe condenser 1,080 along line 1,086 are primarily CO2. However, someH2O vapor would typically be present in the gaseous CO2 and exit thecondenser 1,080 along line 1,086.

The line 1,086 leads to CO2 compressor 1,110. The CO2 compressor 1,110can either be driven from one of the turbines 1,030, 1,050, 1,060 orfrom power from the generator 1,070 or from any other appropriate powersource. The CO2 compressor 1,110 elevates the pressure of the gaseousproducts of combustion entering the CO2 compressor 1,110 along line1,086 to a pressure at which CO2 can be liquefied.

The CO2 compressor discharges the gaseous combustion products along line1,112 which leads to a cooler/condenser 1,120. The cooler/condenser1,120 is cooled with a coolant such as H2O passing along line 1,122 inthe cooler/condenser 1,120. With the increase in pressure resulting frompassage through the CO2 compressor 1,110 and the decreasing temperatureresulting from the cooler/condenser 1,120, the non-CO2 gaseous productsof combustion with boiling points higher than CO2, such as water vapor,are further encouraged to condense into a liquid phase for removal. Aliquid outlet from the cooler/condenser 1,120 leads to line 1,124 whereH2O condensed within the cooler/condenser 1,120 is returned to line1,084 and passed to the feed water pump 1,090. The remaining gaseousproducts of combustion are primarily CO2 passing along line 1,126. Asmall amount of water vapor and some other gases such as argon, oxygenand nitrogen may still be present along with the CO2. Because argon,oxygen and nitrogen are not present in large amounts, they can typicallybe allowed to remain along with the CO2 or removed after liquefaction ofthe CO2 as discussed below. Alternatively, argon can be collected foruse or sale from line 1,134.

The CO2 passes along line 1,126 to a drier 1,128 containing molecularsieves to remove the remaining moisture and exits the drier 1,128 vialine 1,129. Line 1,129 leads to a cooler 1,130. The cooler 1,130 chillsthe CO2 passing along line 1,129 to a temperature below a liquefactiontemperature of CO2 so that the CO2 is liquefied. Preferably, the CO2 iscooled to a temperature of −40° F. at a pressure of 145 psia and exitsthe cooler 1,130 along line 1,132. The cooler 1,130 can be powered in avariety of different manners to provide appropriate heat removal fromthe CO2 passing through the cooler 1,130. Preferably, the cooler 1,130draws heat from the CO2 by routing cooled nitrogen from the airseparation plant 1,010 along lines 1,011 and 1,013 through a heatexchanger with the CO2 passing along line 1,129 to produce the desiredcooling of the CO2 before exiting the cooler 1,130 along line 1,132. Ifnon-liquefaction air separation techniques are utilized in the airseparation plant 1,010, other refrigeration type systems could beutilized in the cooler 1,030 to appropriately cool the CO2 into a liquidphase.

The liquid CO2 can be separated from any gases which have remained withthe CO2 along line 1,132, such as argon or other trace gases which mayhave passed through the system 1,000. The argon or other trace gasesexit cooler 1,130 via line 1,134 and are vented to the atmosphere orducted to an argon recovery system and/or other recovery system asappropriate to economic and emission considerations. The liquid CO2passes along line 1,132 to a CO2 pump 1,140. The CO2 pump 1,140 can bepowered by one of the turbines 1,030, 1050, 1060 or from electricityproduced by the generator 1,070 or from other separate power sources.

The CO2 pump 1,140 preferably pressurizes the CO2 to a pressure matchinga pressure which exists at the depth within a terrestrial formation atwhich the CO2 is to be injected after leaving the pump 1,140 along line1,142. Typically, such pressures would be between 3,000 and 10,000 psia.Such pressures should not exceed the fracture pressures of theformation. Preferably, the pressure of the CO2 in the injection well atthe face of the subterranean formation in which the CO2 is to beinjected should range from a minimum pressure of 10 psia above thepressure of the fluid in the formation to a maximum pressure that isobtained by multiplying the depth of the formation by a factor of 0.8psia per foot of depth.

By liquefying the CO2 before pressurizing it to these high pressures,significantly less energy is required. Alternatively, the CO2 streamexiting secondary cooler/condenser 1,120 via line 1,126 may becompressed through additional stages of compression to a super criticalfluid at the desired pressure rather than liquefied and pumped to a highpressure. The alternative is less energy efficient but may be moreeconomical because of lower capital and/or operating costs.

One means to deliver the CO2 includes use of a pipeline or mobile tanksystem to transport the CO2 to an injection interface, such as a wellhead, above the sequestration site.

The terrestrial formation in which CO2 injection occurs would typicallybe below the water table and can be in the form of a geological porousformation which has been evacuated of liquid fossil fuels and for whichan existing well already exists with a casing capable of handling thepressures involved. Otherwise, wells can be drilled into the designatedgeological formations and then appropriate casings provided in the wellso that migration of the CO2 back up to the surface and into thesurrounding atmosphere is mitigated. A desirable thickness of theformation into which the brine is to be injected is 200 feet or more.Moreover, the CO2 needs to be compatible with formation fluids in orderto minimize reduction of infectivity, or plugging or other formationdamage.

Alternatively, the terrestrial formation can be a deep confined aquiferor a deep ocean location. The high pressure CO2 can be pumped down intoa deep aquifer, sea or ocean location. If the discharge of the CO2 issufficiently deep, the CO2 can remain in a liquid form upon dischargeand will not evaporate into a gaseous phase and migrate to the surface.Other porous geological formations where CO2 can be sequestered includesalt caverns, sulfur caverns and sulfur domes.

Once the CO2 has been separated from other combustion products it couldbe utilized for various different industrial processes where CO2 isrequired, such that the CO2 is not released into the atmosphere.

With particular reference to FIG. 18, a flow chart is provided whichidentifies the materials which are entered into and discharged fromsystem 1,000. Initially air is drawn into an air separator and nitrogengas is released from the air separator. Because nitrogen gas alreadyconstitutes over three-quarters of air, no pollution of the atmosphereresults from this release of nitrogen. Remaining portions of the air arepassed into a gas generator along with a hydrocarbon fuel and waterwhere combustion takes place and combustion products are generated. Thecombustion products are passed through an expander. Power is releasedfrom the expander for any desired use. The combustion products are thenpassed on to a condenser where H2O is released. H2O additionally is nota contaminant of the atmosphere and can be used for a variety ofbeneficial purposes and recycled for use in the gas generator. Remainingcombustion products exit the condenser and are compressed and pumped topressures necessary for their injection into a terrestrial formation.Once injected into the terrestrial formation the CO2 is isolated fromthe atmosphere and the potentially detrimental effects of release oflarge quantities of CO2 into the atmosphere in terms of global warmingand other potential negative atmospheric and environmental effects arethwarted.

Moreover, having thus described the invention it should now be apparentthat various different modifications could be resorted to withoutdeparting from the scope of the invention as disclosed herein and asidentified in the included claims. The above description is provided todisclose the best mode for practicing this invention and to enable oneskilled in the art to practice this invention but should not beconstrued to limit the scope of the invention disclosed herein.

What is claimed is:
 1. A combustion engine providing clean power forvarious applications and featuring low NOx production and low CO2release into the atmosphere, comprising in combination; a source of air,the air including nitrogen and oxygen; a source of fuel, the fuelincluding hydrogen and carbon; an air separator having an inlet coupledto said source of air, a nitrogen separator, an oxygen enriched airoutlet, and a nitrogen outlet separate from said oxygen enriched airoutlet, such that at least a portion of the nitrogen is removed from theair entering said inlet; a fuel combustor, said fuel combustor receivingfuel from said source of fuel and oxygen enriched air from said outletof said air separator, said combustor combusting the fuel with theoxygen enriched air to produce elevated pressure and elevatedtemperature combustion products including H2O and CO2, said combustorhaving a discharge for said combustion products; a combustion productsseparator which separates at least a portion of the H2O from othercombustion products including CO2 coupled to said discharge andincluding an H2O outlet and an exhaust for the other combustion productsincluding CO2; a compressor coupled to said exhaust, said compressorpressurizing fluids passing there through to a pressure aboveatmospheric pressure; and a terrestrial formation injection systemdownstream from said compressor, said injection system coupled to saidcompressor and to a terrestrial formation beneath the atmosphere, saidterrestrial formation capable of holding CO2 therein.
 2. The combustionengine of claim 1 wherein said combustion products separator includes acondenser, said condenser having a temperature and pressure therein atwhich H2O condenses into a liquid phase and at which CO2 remains in agaseous phase.
 3. The combustion engine of claim 2 wherein a cooler isoriented between said exhaust of said combustion products separator andsaid injection system, said cooler having sufficient capability to coolCO2 exiting said combustion products separator at said exhaust to atemperature below a liquefaction temperature for CO2, such that the CO2is liquefied.
 4. The combustion engine of claim 3 wherein said airseparator includes means to cool the air from said source of air to atemperature at which oxygen in the air liquefies for separation of theoxygen from the nitrogen, at least a portion of the nitrogen removedfrom the air directed to said cooler for cooling of the CO2 exiting saidexhaust of said combustion products separator.
 5. The combustion engineof claim 3 wherein a CO2 pump is located between said cooler and saidterrestrial formation injection system, said CO2 pump increasing apressure of the CO2 exiting the exhaust of the combustion productsseparator while the CO2 is in a liquid state.
 6. The combustion engineof claim 3 wherein a combustion product expansion device is interposedbetween said discharge of said fuel combustor and said condenser, saidcombustion product expansion device including means to output power fromsaid engine, said power at least partially used to supply operativepower to said air separator and said compressor; wherein at least aportion of the H2O exiting said condenser through said H2O outlet isrouted through a fluid conduit to said fuel combustor where the H2O iscombined with said combustion products to decrease a temperature of thecombustion products and increase an amount of H2O exiting said dischargeof said fuel combustor; wherein said combustion product expansion deviceincludes three turbines including a high pressure turbine locateddownstream from said discharge of said fuel combustor and upstream froma reheater, said reheater receiving fuel from said source of fuel and O2enriched air from said outlet of said air separator, said reheatercombusting the fuel with the O2 enriched air to produce combustionproducts including H2O and CO2, said reheater also receiving H2O and CO2from said high pressure turbine and mixing said H2O and said CO2 fromsaid high pressure turbine with said H2O and said CO2 generated withinsaid reheater; and an intermediate turbine located downstream from saidreheater and upstream from a low pressure turbine, a feed waterpreheater interposed between an intermediate pressure turbine dischargeand an inlet to said low pressure turbine, said feed water preheaterincluding means to increase a temperature of the H2O exiting said H2Ooutlet of said condenser before said H2O is directed back into said fuelcombustor.
 7. The combustion engine of claim 3 wherein acooler/condenser is located between said compressor and said cooler,said cooler/condenser including means to condense additional H2O vaporexiting said condenser through said exhaust.
 8. The combustion engine ofclaim 5 wherein said CO2 pump includes means to pressurize the fluidspassing there through to a pressure which results in a pressure at saidformation of between 10 psia above a pressure of the fluid in saidformation and 0.8 psia per foot of depth of said formation.
 9. Thecombustion engine of claim 1 wherein said injection system is configuredto deliver the combustion products other than H2O and including CO2beneath the surface of an ocean.
 10. The combustion engine of claim 9wherein said injection system is configured to deliver the combustionproducts including CO2 into a porous underground geological formation.11. The combustion engine of claim 1 wherein said exhaust of saidcombustion products separator discharges primarily CO2 and saidcompressor pressurizes the CO2 until the CO2 becomes a super criticalfluid.
 12. The combustion engine of claim 1 wherein said terrestrialformation injection system is configured to deliver the combustionproducts including CO2 into an aquifer.
 13. A combustion engineproviding clean power for various applications and featuring low NOxproduction and low CO2 release into the atmosphere, comprising incombination: a source of air, the air including nitrogen and oxygen; asource of fuel, the fuel including hydrogen and carbon; an air separatorhaving an inlet coupled to said source of air, a nitrogen separator, anoxygen enriched air outlet, and a nitrogen outlet separate from saidoxygen enriched air outlet, such that at least a portion of the nitrogenis removed from the air entering said inlet; a fuel combustor, said fuelcombustor receiving fuel from said source of fuel and oxygen enrichedair from said outlet of said air separator, said combustor combustingthe fuel with the oxygen enriched air to produce elevated pressure andelevated temperature combustion products including H2O and CO2, saidcombustor having a discharge for said combustion products; a combustionproduct expansion device coupled to said discharge of said combustiondevice, said expansion device outputting power from said system andhaving an exhaust for said combustion products; a condenser coupled tosaid exhaust, said condenser having an H2O outlet for liquid H2O and agaseous combustion product outlet, said condenser configured such thatthe CO2 remains gaseous and exits said combustor through said gaseouscombustion product outlet; a compressor coupled to said gaseouscombustion product outlet, said compressor compressing said gaseouscombustion products to above atmospheric pressure; and a terrestrialformation injection system coupled to said compressor and to aterrestrial formation beneath the atmosphere, said terrestrial formationcapable of holding CO2 therein.
 14. The system of claim 13 wherein saidcompressor has sufficient capability to compress gases passing therethrough to a pressure at which a liquid phase of CO2 can exist.
 15. Thesystem of claim 13 wherein a cooler is interposed between said condenserand said terrestrial formation injection system, said cooler havingsufficient capability to cool the gaseous combustion products to atemperature at which CO2 transitions into a liquid phase.
 16. The systemof claim 15 wherein said terrestrial formation injection system includesa liquid CO2 pump, said liquid CO2 pump including means to furtherpressurize the CO2 passing there through to a pressure corresponding toa pressure existing at a depth within the terrestrial formation intowhich the terrestrial formation injection system is connected, such thatthe CO2 can be delivered into the terrestrial formation at the desireddepth and without release of the CO2 into the atmosphere.
 17. Acombustion engine providing clean power for various applications andfeaturing low NOx production, comprising in combination: a source ofair, the air including nitrogen and oxygen; a source of fuel, the fuelincluding hydrogen and carbon; an air treatment device having an inletcoupled to said source of air, and having an outlet, said air treatmentdevice including means to remove at least a portion of the nitrogen fromthe air entering said inlet; a fuel combustion device, said fuelcombustion device receiving fuel from said source of fuel and O2enriched air from said outlet of said air treatment device, saidcombustion device combusting said fuel with the O2 enriched air toproduce elevated pressure and elevated temperature combustion productsincluding steam, said combustion device having a discharge for saidcombustion products; a combustion product expansion device coupled tosaid discharge of said combustion device, said expansion deviceoutputting power from said engine; wherein said source of fuel includesfuel having both hydrogen and carbon therein; wherein said fuelcombustion device produces elevated pressure and elevated temperaturecombustion products including H2O and CO2; and wherein said expansiondevice includes an exhaust for said combustion products including H2Oand CO2, said exhaust coupled to a condenser, said condenser having anH2O outlet for liquid H2O and a gaseous combustion product outlet, saidgaseous combustion products being a majority CO2, said condenserconfigured such that the CO2 remains gaseous and exits said condenserthrough said gaseous combustion product outlet; whereby CO2 generated bysaid engine is separated from other combustion products for furtherstorage, handling and disposal of the CO2.
 18. The engine of claim 17wherein said gaseous combustion product outlet of said condenser iscoupled to a compressor, said compressor including means to compress thegaseous combustion products including CO2 to a pressure aboveatmospheric pressure; and a terrestrial formation injection systemcoupled to said compressor and to a terrestrial formation beneath theatmosphere, said terrestrial formation capable of holding CO2 thereinwithout substantial release of CO2 into the atmosphere.
 19. The systemof claim 18 wherein said compressor includes means to compress saidgaseous combustion products including CO2 to a pressure at which CO2 canexist in a liquid phase; said compressor having an outlet coupled to acooler, said cooler including means to cool gaseous combustion productsincluding CO2 exiting said compressor to a temperature below aliquefaction temperature of CO2, such that CO2 within the gaseouscombustion products is liquefied; and a CO2 pump including means topressurize said liquefied CO2 up to a pressure corresponding to apressure at a depth within said terrestrial formation at which saidinjection system is configured to inject the CO2.